| 摘要 |
<p>A safety device (3) at vertically movable doors for preventing uncontrolled falling of the door (1) comprises axle (4) which is connected to a door operating apparatus so as to be rotatable with movements of the door and a centrifugal device (9, 11) rotatable by the axle and movable away from the axis of the axle (4) upon rotation of the centrifugal device co-operating with a stop (28) when the axle (4) rotates at a predetermined speed to stop rotation of the axle and thus movement of the door. <IMAGE></p> |
